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Background: The Cytisusratisbonensis group (Fabaceae) includes small shrubs with attractive yellow flowers, used in ornamental cultivation. It is widely distributed in southern forest, forest steppe and steppe zones of Eastern Europe, both in the lowlands and low mountains. This group is notorious for its taxonomic complexity and difficulties in identification, which accounted for incongruent taxonomic treatments and common identification errors, and resulted in a poor understanding of the distribution areas. The increasing availability of herbarium collections and accumulation of human observations through digital resources require their critical taxonomic revision and update in order to provide reliable data for plant species mapping, conservation and analysis of distribution areas. New information: This paper describes a distributional dataset of East European species of the Cytisusratisbonensis group, which was prepared for the pan-European grid mapping project, Atlas Florae Europaeae. The taxonomic revision includes seven species and two interspecific hybrids and is based on the critical evaluation of diagnostic characters, nomenclature and synonymy. The territorial scope of this study is Eastern Europe, but it also includes some data from Central Europe, the Caucasus and the neighbouring territories of Siberia and Kazakhstan, which are included in order to trace eastern and south-eastern limits of the species distributions and to establish reliable synonymy. We report 3699 native occurrence records included in the dataset; these records are based on major herbarium collections which are known to hold specimens from Eastern Europe (DNZ, KRA, KRAM, KW, LE, LW, LWKS, MHA, MSK, MSKH, MSKU, MW), complemented by selected specimens from other herbaria (BUNS, CSAU, H, NNSU, NS, NSK, OXF, PVB, RWBG, TUL). The herbarium collections were examined largely de visu, but partly online. Besides the herbarium specimens, recognisable photographs documenting human observations on online platforms (florafauna.by, iNaturalist, Plantarium, UkrBIN) were also examined and included. All specimen records are accompanied with textual data and georeferences, which were produced for this dataset. Point and contour distribution maps are created for each accepted species. According to the distributional data, the Cytisusratisbonensis group may be classified as temperate lowland and steppic in Eastern Europe. Among European endemic shrubs, C.cinereus (as C.paczoskii) was assessed in 2017 as Near Threatened, whereas its new IUCN protection status is proposed as Least Concern because the new data demonstrated that its distribution area is much greater than previously believed. A species restricted to the Crimea, C.wulffii, is assessed here for the first time as Vulnerable because of its restricted area and small population size (criteria D1,2).
RESUMO
A few species names in Cytisussect.Tubocytisus are re-assessed and taxonomically evaluated. Diagnostic characters are discussed and the species status of C.absinthioides Janka, C.eriocarpus Boiss., C.frivaldszkyanus Degen, C.jankae Velen. and C.smyrnaeus Boiss. is confirmed. The holotype of Cytisustriflorus Lam. was found to belong to C.hirsutus L. rather than to the C.ratisbonensis group as currently treated. Cytisuslasiosemius Boiss. is not the correct name for C.frivaldszkyanus Degen, but another synonym of C.hirsutus. Cytisuslitwinowii V.I.Krecz., which was known solely from the holotype, is a synonym of C.austriacus L. s.str. Chamaecytisuspseudojankae Pifkó & Barina, reported from a small area shared between Albania, Greece and North Macedonia, is treated as a subalpine variant of C.austriacus. Cytisustmoleus Boiss. is removed from the synonymy of C.eriocarpus and added to the synonymy of C.pygmaeus Willd. Cytisusfalcatussubsp.albanicus Degen & Dörfl. and C.pubescens Gilib. are synonymised with C.hirsutus. Cytisusmicrophyllus Boiss. is moved from C.austriacus s.l. to the synonymy of C.frivaldszkyanus, and C.pindicola (Degen) Halácsy to the synonymy of C.jankae. Chamaecytisuscalcareus (Velen.) Kuzmanov is accepted as Cytisuscalcareus (Velen.) Sennikov & Val.N.Tikhom., comb. nov., and its distribution is circumscribed. Cytisushirsutusvar.ciliatus (Wahlenb.) Hazsl. and C.polytrichusvar.subglabratus Val.N.Tikhom. & Sennikov, var. nov. are recognised as glabrous variants of the corresponding species. Lectotypes of C.ciliatus, C.hirsutissimus K.Koch, C.jankae, C.lasiosemius, C.pubescens, C.rhodopeus J.Wagner ex Bornm. and C.thirkeanus K.Koch are designated. Cytisuspolytrichus is reported from the Western Caucasus in place of C.wulffii auct.
RESUMO
A group of species of Cytisussect.Tubocytisus with strictly lateral inflorescences, commonly referred to as C.ratisbonensis s.l., is critically revised in Eastern Europe on the basis of morphology and comprehensive treatment of herbarium specimens and observations. Seven species and two presumed hybrids are recognised. Complete accounts are provided for each species, with synonyms, typifications, brief morphological descriptions, data on ecology and distributions, taxonomic and nomenclatural annotations. Cytisuspolonicus is described as new to science, separated from C.ratisbonensis on the basis of morphology and diploid (vs. tetraploid) chromosome count. The lectotype of C.elongatus is superseded and a new lectotype is designated; this name has priority for the species previously known as C.triflorus. Six species names are newly placed to the synonymy: Chamaecytisuspineticola under Cytisusruthenicus s. str., and Cytisusczerniaevii, C.leucotrichus, C.lindemannii, C.ponomarjovii and Chamaecytisuskorabensis under Cytisuselongatus. The presumed hybrid between C.ruthenicus and C.elongatus, which was incorrectly known as C.czerniaevii, is described here as C.semerenkoanus. Cytisuslithuanicus, which has been an obscure name since its original publication, is resurrected for a newly-recognised octoploid species, which is endemic to eastern Poland, western Belarus and north-western Ukraine. The name C.cinereus is re-instated for the species previously known as C.paczoskii, and C.horniflorus is added to its synonymy; its complete distribution area is circumscribed, and its occurrence in Austria, Poland, Romania, Serbia and Slovakia is documented. Cytisuskreczetoviczii and C.elongatus are reported for the first time from Belarus, and the latter species also from Bosnia and Herzegovina, Montenegro and Slovenia. Cytisusborysthenicus and C.elongatus are reported as new to some territories in European Russia. Cytisusratisbonensis s. str. is treated as absent from Eastern Europe. The neglected protologue of C.ruthenicus is discovered, and the nomenclature of all other names is verified and corrected when necessary. The original material of C.borysthenicus is re-discovered. Five further lectotypes and one neotype are designated. Distribution areas are circumscribed on the basis of numerous herbarium collections and documented observations, identified or verified by the authors. Chromosome counts published for nameless taxa from Belarus, Ukraine and Russia are assigned to the species according to their herbarium vouchers: C.borysthenicus, C.kreczetoviczii and C.lithuanicus are octoploid (2n = 100), C.ruthenicus is tetraploid (2n = 50) and octoploid (2n = 100), and C.semerenkoanus and C.elongatus are tetraploid (2n = 50).